The invention relates to a method for the preparation of hemodialysis fluid containing bicarbonate ions. For one hemodialysis treatment approximately 120-180 liters of dialysis fluid are required, a typical composition of which is as follows:
______________________________________ Concentration Component (mmol/liter) ______________________________________ Na.sup.+ 139 K.sup.+ 2.5 Ca.sup.++ 1.65 Mg.sup.++ 0.6 Cl.sup.- 111 HCO.sub.3.sup.- 32 acetate.sup.- 3 ______________________________________
The problems in selecting a suitable composition of the dialysis fluid, adapted to the physiological requirements, are, for example, discussed in the publication "Replacement of Renal Function by Dialysis" (Editor: W. Drukker, F. M. Parsons, J. F. Maher; Martinus Nijhoff Medical Division, Den Haag 1978) in the chapter "The Composition of Dialysis Fluid" (Author: F. M. Parsons, A. M. Davison). More recent information is found in the book "Blutreinigungsverfahren" ["Methods of blood purification"] (Editor: H. E. Franz, 4th Edition; Georg Thieme Verlag; Stuttgart, N.Y., 1990) and the literature cited therin. It is well known and also apparant from these publications, that to adapt the composition of dialysis fluids to the individual state of disease of each single patient is one of the main requirements for an optimization of hemodialysis treatment.
This question requires increased attention with regard to patients suffering from additional acute or chronic diseases, while also considering children, elderly and weak patients, and cases of acute renal failure. In these cases it is frequently necessary to correct the composition of the dialysis fluid on the basis of actual diagnostic results and taking into account the additional therapeutical measures applied. But also for the "normal" patient the composition should be carefully adapted in order to prevent long-term damages.
The technical means for an individual adaptation of dialysis fluids are however still inadequate. There is no system available which would be easy to handle and solve the problem at an acceptably low cost and with simple technical equipment.
The occurence of negative dialysis side-effects may be reduced by changing the concentration of certain constituents of the dialysis fluid in the course of a treatment session continuously or in discrete steps. This method is known as "profiling" a dialysis fluid. With respect to cardiovascular instabiliy it has been found especially advantageous to apply a high sodium concentration (e.g. 150 mmol/liter) in the first phase and a low sodium concentration (e.g. 130 mmol/Liter) in the final phase. For patients with a high blood potassium level, particularly in cases of acute renal failure, a quick reduction of the potassium level may be dangerous. It is therefore recommended to use a dialyis fluid of high potassium concentration initally and to reduce the potassium level in steps down to zero until the end of the session.
Procedures of this kind, deemed important from the medical point of view, are not sufficiently supported by existing methods and equipment.